A few years ago, someone dubbed Sarah Blacker “Sundress Rocker” and the nickname stuck. Playing solo acoustic guitar on songs like the ebullient and playful “Perfectly Imperfect,” she could bring a warm breeze to any cool day. But the folksinger harbored a secret desire — to plug in. With her new album, In Waves, Blacker turns to the latter half of that moniker and unleashes the rocker within.

“I get to play electric guitar on the whole record,” Blacker said excitedly in a recent interview. “That was the most fun, to just rock out and take an adventure to a territory that I have wanted to go.”

The results reflect her unique musical perspective.

“It’s tough for a singer-songwriter because if you write in a lot of styles you don’t really know where to put yourself,” Blacker said. “I’ve never really felt like I fit into the folk scene, but at the same time I’m not hip enough to be indie.”

One critic called the record “fearless,” and Blacker agreed with the assessment.

“Fearlessness is where I am at in my life as a person, too,” she said. “Obviously, we all have our own journey through finding ourselves and being a confident person. At this point, I just think I don’t care what people think about me. That’s not in a bad way; I just know who I am. I celebrate my freakishness.”

There are traces of Blacker’s past persona on the new disc. “Exhale” is a gently crafted paean to unexpected love with the brilliant couplet, “I told you where the line between my lips and my heart was strung/your eyes said you saw it but like your six-string you gave it a strum.” She rocks the ukulele on another tune called “It Shows.”

But there’s a moment on the instrumental “Interlude” that captures the essence of In Waves. It begins with electric guitar plucking that gives way to dreamy feedback. Blacker then commences to kick out the jams with authority on the fittingly titled “Breakout.” Other standouts include “Way Like Water,” which opens the disc, and the rollicking title track, a love song Blacker said was written for a specific person, “but it’s not for them anymore.”

The Web page for In Waves said it was “written in love, recorded in heartbreak,” but Blacker is in a better place these days. She’s spending a lot of time with Aaron Katz, a veteran of seminal Seacoast band Percy Hill and The Dejas. Katz will join her on drums and percussion for a show Friday, Dec. 11, at Concord’s True Brew Barista.

“We’ll be playing a fun lively set that I think will go over well for that room,” Blacker said.

Blacker has roots in the Concord area, but hasn’t played west of Portsmouth in five or six years.

“I did Penuche’s Ale House and a couple of others, but it’s been a long time,” she said.

The set features jazz-like improvisation.

“The way I play guitar and Aaron is a percussionist, we’ve both found a connection rhythmically,” she said. “It’s been fun to experiment with a lot of rhythms and just let the music become like a space for people to dance and then with my voice — which I have always considered to be my principal instrument — improvise melodies and kind of use it like a jazz trumpet.”

With Katz, she’s found a way to explore her free-form side.

“I used to consider myself a jam band,” she said with a laugh. “Now I’m working with somebody who was in a very successful one and we speak the same language. … We can take the songs and let them breathe, just kind of pull them out of their form and see what happens.”

Turning up the volume is also a treat, however.

“I think I have always been a rock and roller at heart but because I play the acoustic guitar, things kind of came out on the quieter side,” Blacker said. “I do like to write a good ballad. But at the same time, I feel like I have rock and roll in my blood, so I’m moving more in that direction.”